The proposed project is designed to define the mechanisms of control of the smooth muscle of the mammalian oviduct. We have shown that electrical activity, which triggers contractions, changes profoundly following ovulation and frequently, the deviation from randomness and the distance which contractions propagate appear to control the timing of ovum transport to the uterus and is a site of hormonal action. The contraction process is also altered by ovulation and hormones. The effects of hormones and the ionic environment on in vitro electrical activity of rabbit, guinea pig and human oviducts will be studied as well as the mechanisms which control frequency and direction and distance of propagation of electrical activity. These changes will be correlated with changes in the membrane potential of cells, the distribution of ions across the cell membrane and the ultrastructure of cell-to-cell contacts. The mechanisms whereby calcium, essential to contraction, is stored, released and sequestered, and the contraction process will be studied in oviducts removed during ovum transport.